Quantitative Analysis of Lactone Enantiomers in Butter and Margarine through the Combination of Solvent Extraction and Enantioselective Gas Chromatography-Mass Spectrometry.

We quantified the enantiomeric distributions of δ- and γ-lactones in butter, fermented butter, and margarine through the combination of solvent extraction and enantioselective gas chromatography-mass spectrometry. The main lactones in butter and fermented butter comprised (R)-δ-decalactone, (R)-δ-dodecalactone, (R)-δ-tetradecalactone, (R)-δ-hexadecalactone, and (R)-γ-dodecalactone. In contrast, margarine samples consisted of only δ-decalactone and δ-dodecalactone in racemic forms, indicating that synthetic aroma chemicals were added to margarine. After heat treatment, 13 types of lactones were detected in butter and fermented butter. In heated butter and fermented butter, major δ-lactones in the (R)-form were abundant, but only δ-octalactone in the (S)-form was detected. In contrast, γ-dodecalactone (main γ-lactone in the heated samples) was abundant in the (R)-form, whereas other γ-lactones were detected in the racemic form. These results suggested that the major lactones in dairy products are in the (R)-form. Furthermore, the heat treatment affected the enantiomeric distribution of lactones in butter and fermented butter.